/* ******************************************************************************* * Copyright (C) 2010-2012, International Business Machines * Corporation and others. All Rights Reserved. ******************************************************************************* * file name: ucharstrie.h * encoding: US-ASCII * tab size: 8 (not used) * indentation:4 * * created on: 2010nov14 * created by: Markus W. Scherer */ #ifndef __UCHARSTRIE_H__ #define __UCHARSTRIE_H__ /** * \file * \brief C++ API: Trie for mapping Unicode strings (or 16-bit-unit sequences) * to integer values. */ #include "unicode/utypes.h" #include "unicode/unistr.h" #include "unicode/uobject.h" #include "unicode/ustringtrie.h" U_NAMESPACE_BEGIN class Appendable; class UCharsTrieBuilder; class UVector32; /** * Light-weight, non-const reader class for a UCharsTrie. * Traverses a UChar-serialized data structure with minimal state, * for mapping strings (16-bit-unit sequences) to non-negative integer values. * * This class owns the serialized trie data only if it was constructed by * the builder's build() method. * The public constructor and the copy constructor only alias the data (only copy the pointer). * There is no assignment operator. * * This class is not intended for public subclassing. * @stable ICU 4.8 */ class U_COMMON_API UCharsTrie : public UMemory { public: /** * Constructs a UCharsTrie reader instance. * * The trieUChars must contain a copy of a UChar sequence from the UCharsTrieBuilder, * starting with the first UChar of that sequence. * The UCharsTrie object will not read more UChars than * the UCharsTrieBuilder generated in the corresponding build() call. * * The array is not copied/cloned and must not be modified while * the UCharsTrie object is in use. * * @param trieUChars The UChar array that contains the serialized trie. * @stable ICU 4.8 */ UCharsTrie(const UChar *trieUChars) : ownedArray_(NULL), uchars_(trieUChars), pos_(uchars_), remainingMatchLength_(-1) {} /** * Destructor. * @stable ICU 4.8 */ ~UCharsTrie(); /** * Copy constructor, copies the other trie reader object and its state, * but not the UChar array which will be shared. (Shallow copy.) * @param other Another UCharsTrie object. * @stable ICU 4.8 */ UCharsTrie(const UCharsTrie &other) : ownedArray_(NULL), uchars_(other.uchars_), pos_(other.pos_), remainingMatchLength_(other.remainingMatchLength_) {} /** * Resets this trie to its initial state. * @return *this * @stable ICU 4.8 */ UCharsTrie &reset() { pos_=uchars_; remainingMatchLength_=-1; return *this; } /** * UCharsTrie state object, for saving a trie's current state * and resetting the trie back to this state later. * @stable ICU 4.8 */ class State : public UMemory { public: /** * Constructs an empty State. * @stable ICU 4.8 */ State() { uchars=NULL; } private: friend class UCharsTrie; const UChar *uchars; const UChar *pos; int32_t remainingMatchLength; }; /** * Saves the state of this trie. * @param state The State object to hold the trie's state. * @return *this * @see resetToState * @stable ICU 4.8 */ const UCharsTrie &saveState(State &state) const { state.uchars=uchars_; state.pos=pos_; state.remainingMatchLength=remainingMatchLength_; return *this; } /** * Resets this trie to the saved state. * If the state object contains no state, or the state of a different trie, * then this trie remains unchanged. * @param state The State object which holds a saved trie state. * @return *this * @see saveState * @see reset * @stable ICU 4.8 */ UCharsTrie &resetToState(const State &state) { if(uchars_==state.uchars && uchars_!=NULL) { pos_=state.pos; remainingMatchLength_=state.remainingMatchLength; } return *this; } /** * Determines whether the string so far matches, whether it has a value, * and whether another input UChar can continue a matching string. * @return The match/value Result. * @stable ICU 4.8 */ UStringTrieResult current() const; /** * Traverses the trie from the initial state for this input UChar. * Equivalent to reset().next(uchar). * @param uchar Input char value. Values below 0 and above 0xffff will never match. * @return The match/value Result. * @stable ICU 4.8 */ inline UStringTrieResult first(int32_t uchar) { remainingMatchLength_=-1; return nextImpl(uchars_, uchar); } /** * Traverses the trie from the initial state for the * one or two UTF-16 code units for this input code point. * Equivalent to reset().nextForCodePoint(cp). * @param cp A Unicode code point 0..0x10ffff. * @return The match/value Result. * @stable ICU 4.8 */ UStringTrieResult firstForCodePoint(UChar32 cp); /** * Traverses the trie from the current state for this input UChar. * @param uchar Input char value. Values below 0 and above 0xffff will never match. * @return The match/value Result. * @stable ICU 4.8 */ UStringTrieResult next(int32_t uchar); /** * Traverses the trie from the current state for the * one or two UTF-16 code units for this input code point. * @param cp A Unicode code point 0..0x10ffff. * @return The match/value Result. * @stable ICU 4.8 */ UStringTrieResult nextForCodePoint(UChar32 cp); /** * Traverses the trie from the current state for this string. * Equivalent to * \code * Result result=current(); * for(each c in s) * if(!USTRINGTRIE_HAS_NEXT(result)) return USTRINGTRIE_NO_MATCH; * result=next(c); * return result; * \endcode * @param s A string. Can be NULL if length is 0. * @param length The length of the string. Can be -1 if NUL-terminated. * @return The match/value Result. * @stable ICU 4.8 */ UStringTrieResult next(const UChar *s, int32_t length); /** * Returns a matching string's value if called immediately after * current()/first()/next() returned USTRINGTRIE_INTERMEDIATE_VALUE or USTRINGTRIE_FINAL_VALUE. * getValue() can be called multiple times. * * Do not call getValue() after USTRINGTRIE_NO_MATCH or USTRINGTRIE_NO_VALUE! * @return The value for the string so far. * @stable ICU 4.8 */ inline int32_t getValue() const { const UChar *pos=pos_; int32_t leadUnit=*pos++; // U_ASSERT(leadUnit>=kMinValueLead); return leadUnit&kValueIsFinal ? readValue(pos, leadUnit&0x7fff) : readNodeValue(pos, leadUnit); } /** * Determines whether all strings reachable from the current state * map to the same value. * @param uniqueValue Receives the unique value, if this function returns TRUE. * (output-only) * @return TRUE if all strings reachable from the current state * map to the same value. * @stable ICU 4.8 */ inline UBool hasUniqueValue(int32_t &uniqueValue) const { const UChar *pos=pos_; // Skip the rest of a pending linear-match node. return pos!=NULL && findUniqueValue(pos+remainingMatchLength_+1, FALSE, uniqueValue); } /** * Finds each UChar which continues the string from the current state. * That is, each UChar c for which it would be next(c)!=USTRINGTRIE_NO_MATCH now. * @param out Each next UChar is appended to this object. * @return the number of UChars which continue the string from here * @stable ICU 4.8 */ int32_t getNextUChars(Appendable &out) const; /** * Iterator for all of the (string, value) pairs in a UCharsTrie. * @stable ICU 4.8 */ class U_COMMON_API Iterator : public UMemory { public: /** * Iterates from the root of a UChar-serialized UCharsTrie. * @param trieUChars The trie UChars. * @param maxStringLength If 0, the iterator returns full strings. * Otherwise, the iterator returns strings with this maximum length. * @param errorCode Standard ICU error code. Its input value must * pass the U_SUCCESS() test, or else the function returns * immediately. Check for U_FAILURE() on output or use with * function chaining. (See User Guide for details.) * @stable ICU 4.8 */ Iterator(const UChar *trieUChars, int32_t maxStringLength, UErrorCode &errorCode); /** * Iterates from the current state of the specified UCharsTrie. * @param trie The trie whose state will be copied for iteration. * @param maxStringLength If 0, the iterator returns full strings. * Otherwise, the iterator returns strings with this maximum length. * @param errorCode Standard ICU error code. Its input value must * pass the U_SUCCESS() test, or else the function returns * immediately. Check for U_FAILURE() on output or use with * function chaining. (See User Guide for details.) * @stable ICU 4.8 */ Iterator(const UCharsTrie &trie, int32_t maxStringLength, UErrorCode &errorCode); /** * Destructor. * @stable ICU 4.8 */ ~Iterator(); /** * Resets this iterator to its initial state. * @return *this * @stable ICU 4.8 */ Iterator &reset(); /** * @return TRUE if there are more elements. * @stable ICU 4.8 */ UBool hasNext() const; /** * Finds the next (string, value) pair if there is one. * * If the string is truncated to the maximum length and does not * have a real value, then the value is set to -1. * In this case, this "not a real value" is indistinguishable from * a real value of -1. * @param errorCode Standard ICU error code. Its input value must * pass the U_SUCCESS() test, or else the function returns * immediately. Check for U_FAILURE() on output or use with * function chaining. (See User Guide for details.) * @return TRUE if there is another element. * @stable ICU 4.8 */ UBool next(UErrorCode &errorCode); /** * @return The string for the last successful next(). * @stable ICU 4.8 */ const UnicodeString &getString() const { return str_; } /** * @return The value for the last successful next(). * @stable ICU 4.8 */ int32_t getValue() const { return value_; } private: UBool truncateAndStop() { pos_=NULL; value_=-1; // no real value for str return TRUE; } const UChar *branchNext(const UChar *pos, int32_t length, UErrorCode &errorCode); const UChar *uchars_; const UChar *pos_; const UChar *initialPos_; int32_t remainingMatchLength_; int32_t initialRemainingMatchLength_; UBool skipValue_; // Skip intermediate value which was already delivered. UnicodeString str_; int32_t maxLength_; int32_t value_; // The stack stores pairs of integers for backtracking to another // outbound edge of a branch node. // The first integer is an offset from uchars_. // The second integer has the str_.length() from before the node in bits 15..0, // and the remaining branch length in bits 31..16. // (We could store the remaining branch length minus 1 in bits 30..16 and not use the sign bit, // but the code looks more confusing that way.) UVector32 *stack_; }; private: friend class UCharsTrieBuilder; /** * Constructs a UCharsTrie reader instance. * Unlike the public constructor which just aliases an array, * this constructor adopts the builder's array. * This constructor is only called by the builder. */ UCharsTrie(UChar *adoptUChars, const UChar *trieUChars) : ownedArray_(adoptUChars), uchars_(trieUChars), pos_(uchars_), remainingMatchLength_(-1) {} // No assignment operator. UCharsTrie &operator=(const UCharsTrie &other); inline void stop() { pos_=NULL; } // Reads a compact 32-bit integer. // pos is already after the leadUnit, and the lead unit has bit 15 reset. static inline int32_t readValue(const UChar *pos, int32_t leadUnit) { int32_t value; if(leadUnit<kMinTwoUnitValueLead) { value=leadUnit; } else if(leadUnit<kThreeUnitValueLead) { value=((leadUnit-kMinTwoUnitValueLead)<<16)|*pos; } else { value=(pos[0]<<16)|pos[1]; } return value; } static inline const UChar *skipValue(const UChar *pos, int32_t leadUnit) { if(leadUnit>=kMinTwoUnitValueLead) { if(leadUnit<kThreeUnitValueLead) { ++pos; } else { pos+=2; } } return pos; } static inline const UChar *skipValue(const UChar *pos) { int32_t leadUnit=*pos++; return skipValue(pos, leadUnit&0x7fff); } static inline int32_t readNodeValue(const UChar *pos, int32_t leadUnit) { // U_ASSERT(kMinValueLead<=leadUnit && leadUnit<kValueIsFinal); int32_t value; if(leadUnit<kMinTwoUnitNodeValueLead) { value=(leadUnit>>6)-1; } else if(leadUnit<kThreeUnitNodeValueLead) { value=(((leadUnit&0x7fc0)-kMinTwoUnitNodeValueLead)<<10)|*pos; } else { value=(pos[0]<<16)|pos[1]; } return value; } static inline const UChar *skipNodeValue(const UChar *pos, int32_t leadUnit) { // U_ASSERT(kMinValueLead<=leadUnit && leadUnit<kValueIsFinal); if(leadUnit>=kMinTwoUnitNodeValueLead) { if(leadUnit<kThreeUnitNodeValueLead) { ++pos; } else { pos+=2; } } return pos; } static inline const UChar *jumpByDelta(const UChar *pos) { int32_t delta=*pos++; if(delta>=kMinTwoUnitDeltaLead) { if(delta==kThreeUnitDeltaLead) { delta=(pos[0]<<16)|pos[1]; pos+=2; } else { delta=((delta-kMinTwoUnitDeltaLead)<<16)|*pos++; } } return pos+delta; } static const UChar *skipDelta(const UChar *pos) { int32_t delta=*pos++; if(delta>=kMinTwoUnitDeltaLead) { if(delta==kThreeUnitDeltaLead) { pos+=2; } else { ++pos; } } return pos; } static inline UStringTrieResult valueResult(int32_t node) { return (UStringTrieResult)(USTRINGTRIE_INTERMEDIATE_VALUE-(node>>15)); } // Handles a branch node for both next(uchar) and next(string). UStringTrieResult branchNext(const UChar *pos, int32_t length, int32_t uchar); // Requires remainingLength_<0. UStringTrieResult nextImpl(const UChar *pos, int32_t uchar); // Helper functions for hasUniqueValue(). // Recursively finds a unique value (or whether there is not a unique one) // from a branch. static const UChar *findUniqueValueFromBranch(const UChar *pos, int32_t length, UBool haveUniqueValue, int32_t &uniqueValue); // Recursively finds a unique value (or whether there is not a unique one) // starting from a position on a node lead unit. static UBool findUniqueValue(const UChar *pos, UBool haveUniqueValue, int32_t &uniqueValue); // Helper functions for getNextUChars(). // getNextUChars() when pos is on a branch node. static void getNextBranchUChars(const UChar *pos, int32_t length, Appendable &out); // UCharsTrie data structure // // The trie consists of a series of UChar-serialized nodes for incremental // Unicode string/UChar sequence matching. (UChar=16-bit unsigned integer) // The root node is at the beginning of the trie data. // // Types of nodes are distinguished by their node lead unit ranges. // After each node, except a final-value node, another node follows to // encode match values or continue matching further units. // // Node types: // - Final-value node: Stores a 32-bit integer in a compact, variable-length format. // The value is for the string/UChar sequence so far. // - Match node, optionally with an intermediate value in a different compact format. // The value, if present, is for the string/UChar sequence so far. // // Aside from the value, which uses the node lead unit's high bits: // // - Linear-match node: Matches a number of units. // - Branch node: Branches to other nodes according to the current input unit. // The node unit is the length of the branch (number of units to select from) // minus 1. It is followed by a sub-node: // - If the length is at most kMaxBranchLinearSubNodeLength, then // there are length-1 (key, value) pairs and then one more comparison unit. // If one of the key units matches, then the value is either a final value for // the string so far, or a "jump" delta to the next node. // If the last unit matches, then matching continues with the next node. // (Values have the same encoding as final-value nodes.) // - If the length is greater than kMaxBranchLinearSubNodeLength, then // there is one unit and one "jump" delta. // If the input unit is less than the sub-node unit, then "jump" by delta to // the next sub-node which will have a length of length/2. // (The delta has its own compact encoding.) // Otherwise, skip the "jump" delta to the next sub-node // which will have a length of length-length/2. // Match-node lead unit values, after masking off intermediate-value bits: // 0000..002f: Branch node. If node!=0 then the length is node+1, otherwise // the length is one more than the next unit. // For a branch sub-node with at most this many entries, we drop down // to a linear search. static const int32_t kMaxBranchLinearSubNodeLength=5; // 0030..003f: Linear-match node, match 1..16 units and continue reading the next node. static const int32_t kMinLinearMatch=0x30; static const int32_t kMaxLinearMatchLength=0x10; // Match-node lead unit bits 14..6 for the optional intermediate value. // If these bits are 0, then there is no intermediate value. // Otherwise, see the *NodeValue* constants below. static const int32_t kMinValueLead=kMinLinearMatch+kMaxLinearMatchLength; // 0x0040 static const int32_t kNodeTypeMask=kMinValueLead-1; // 0x003f // A final-value node has bit 15 set. static const int32_t kValueIsFinal=0x8000; // Compact value: After testing and masking off bit 15, use the following thresholds. static const int32_t kMaxOneUnitValue=0x3fff; static const int32_t kMinTwoUnitValueLead=kMaxOneUnitValue+1; // 0x4000 static const int32_t kThreeUnitValueLead=0x7fff; static const int32_t kMaxTwoUnitValue=((kThreeUnitValueLead-kMinTwoUnitValueLead)<<16)-1; // 0x3ffeffff // Compact intermediate-value integer, lead unit shared with a branch or linear-match node. static const int32_t kMaxOneUnitNodeValue=0xff; static const int32_t kMinTwoUnitNodeValueLead=kMinValueLead+((kMaxOneUnitNodeValue+1)<<6); // 0x4040 static const int32_t kThreeUnitNodeValueLead=0x7fc0; static const int32_t kMaxTwoUnitNodeValue= ((kThreeUnitNodeValueLead-kMinTwoUnitNodeValueLead)<<10)-1; // 0xfdffff // Compact delta integers. static const int32_t kMaxOneUnitDelta=0xfbff; static const int32_t kMinTwoUnitDeltaLead=kMaxOneUnitDelta+1; // 0xfc00 static const int32_t kThreeUnitDeltaLead=0xffff; static const int32_t kMaxTwoUnitDelta=((kThreeUnitDeltaLead-kMinTwoUnitDeltaLead)<<16)-1; // 0x03feffff UChar *ownedArray_; // Fixed value referencing the UCharsTrie words. const UChar *uchars_; // Iterator variables. // Pointer to next trie unit to read. NULL if no more matches. const UChar *pos_; // Remaining length of a linear-match node, minus 1. Negative if not in such a node. int32_t remainingMatchLength_; }; U_NAMESPACE_END #endif // __UCHARSTRIE_H__